Well... I won't buy one for real, or in-game. I don't buy things from Trade or the AH... so the "economy" doesn't really affect me.
It probably won't affect anyone, but they'll complain about it nonetheless.
I guess it can help against illegal gold selling, and the hacking and scamming that supports it.
Then again, that all depends on the market price in gold of the cubs, and how many people actually want them on a given server. Since it is a one-each permanent item, there is an upper limit on how many can be sold for gold per server.
I can't imagine a gold market price high enough to make the cash investment worth it while still keeping enough demand. Especially not one high enough to "break" the in-game "economy", quotes because you can't break an economy that barely behaves like an economy. I mean, I'd want a substantial amount of gold for $10, but not everyone is going to pay that much for one, and folks might just spend the $10 if they really want one, rather than relying on buying it from another player for gold.
So, in reality, meh, this changes very little. Though, it won't stop the forums and chat channels from exploding over it.